Remove the giblets from the chicken and reserve everything but the liver (it makes the stock bitter). Rinse the chicken with cool water. Put the chicken and giblets in a large stockpot. Toss in the yellow onion, green onions, garlic, ginger, and peppercorns. Pour about 3 quarts of cold water into the pot to cover the chicken by 1 inch and bring it to a simmer over medium heat. Skim off the foam, reduce the heat and simmer gently, uncovered, for 1 hour or until the chicken is cooked through. Skim off the foam that rises to the surface periodically. Add a little more water if necessary to keep the chicken covered while simmering.
Carefully remove the chicken from the pot and let it cool. Pull the meat off the bones. Remove the skin and shred the meat by hand into a storage container; reserve for soups and salads.
In the meantime, set a large fine sieve or a large strainer lined with cheesecloth (the cheesecloth will remove some of the excess fat) over another pot. Pour the stock into the sieve or strainer to strain out the vegetable solids; discard. Use the stock immediately or if you plan on storing it, put the pot in a sink full of ice water and chill it down, stirring every now and then. Transfer to a storage container, cover, and refrigerate for up to one week, or freeze.
Edited: October 15th, 2009